While heat development, for example, of a high-economy, performance-optimized diesel engine, can be very low on the cylinder crankshaft housing, this low heat development in no way applies to “hot zones” such as in manifolds, turbochargers, catalytic converters, etc. Due to the more and more compact construction of engines, components not thermally “compatible” are increasingly being in close proximity to one another. Accordingly, it is necessary to protect thermal engine components against bordering, heat-sensitive assemblies, such as sensors, fuel lines, pressure cells, body parts, etc. using so-called shielding components, such as heat shields. The situation is also exacerbated by the compact structure in that the high packing density of the assemblies constricts the cooling air flow in the engine compartment. Noise abatement measures can also contribute to this situation. For example, plastic bottom plates designed to reduce the emission of noise from the engine compartment to the roadway, under certain circumstances can produce effective insulation with which heat is enclosed in the engine compartment. Catalytic converters, due to their phased high surface temperature, are considered to be among the heat sources necessitating the use of protective shield barriers. One typical example of this situation is construction measures, such as positioning the catalytic converter close by on the manifold. This design principle performs the function of rapid heat-up of the catalytic converter, and thus, of reducing emissions in the cold start phase, and shifts a major source of heat into the engine compartment where numerous assemblies are crowded in a tight space. Certainly one reason for the growing importance of shielding components, such as heat shields, is the trend toward use of thermoplastics. The light and economical materials with their exceptional moldability are rapidly becoming common in the engine compartment, but require special attention with respect to ambient temperatures at the application site relative to other thermal engine parts (“New materials and development tools for heat protection”, in MTZ 12/2001, Vol. 72, pp. 1044 ff).
DE 102 47 641 B3 discloses a generic structural component, especially in the form of a noise-damping shielding component, as a component of a motor vehicle. To improve acoustic insulation in the known structural component, the pertinent shielding component has a shielding body with a base edge as a structural part of a first type which can be fixed on the edge side by angular bracket legs within the engine compartment on stationary parts there, and which shields thermal engine components relative to heat-sensitive components.
The shielding body, as a structural part of the first type, is configured overall, viewed in cross section, as an angle, and has a symmetrical structure in this respect. The angled middle area undergoes transition on the edge side into areas of greater curvature that join bridge-like terminations extending in a straight line. On the respective two opposing edge areas, the angular brackets are mounted subsequently as fixing means. In the known solution, the shielding body has two layers of sheet metal, between which an acoustically insulating and/or heat insulating layer extends. To fix the sheet metal cover layers to one another, flanging is used in which the free flange edge of one cover layer superficially encompasses the edge area of the other cover layer. To reduce weight, the shielding body is made of aluminum or some other lightweight metal.
The known solution is used preferably for shielding a clutch between the gearbox flange and the universal shaft against solid-borne noise originating from the transmission and against the continuing influence of temperature radiation of the exhaust pipe extending adjacent to it. In tests, a reduction of acoustic emission in the known solution by 3 dB was achieved. To achieve the pertinent shielding action, along the middle area of the first structural part in the form of a shielding body, other structural parts of a second type extend in the form of bead-shaped longitudinal and transverse ribs over the outer side of the shielding body. It is characteristic of this known structuring that the longitudinal ribs extending over the entire length of the shielding body and positioned in the longitudinal orientation of the structural part of the first type are adjoined by transverse ribs which are integrally molded on, which form a type of nub structure and which in an alternating sequence fit adjacently into the intermediate spaces between the two respective transverse ribs of an adjacent longitudinal rib. The edge areas which are bent off more dramatically to the outside with the connecting brackets are conversely kept free of the ribs. With regard to the interrupted transverse rib structure of the known solution, it can be expected that in this respect stiffness and strength are reduced. Furthermore, at the transition point to the connecting brackets, stiffening of the shielding body is obtained only by the bent bracket legs which largely define the connection geometry, in this instance of the structural component, on the stationary engine or chassis components. In this way, the possible applications of the known structural component are limited. The connecting brackets with their bent bracket legs and eye connecting points for the penetration of a fastener (screw) require installation space and increase the weight for the known solution.